Scotland's largest teaching union is demanding schools and councils follow health advice to protect pupils and staff from coronavirus.
The Education Institute of Scotland (EIS) has accused some local authorities of not following guidelines around Covid-19.
The union claims some schools have been allowing cohorts of pupils to attend unnecessarily and certain councils have been holding large staff meetings where social distancing is impossible.
Last week, the Scottish Government ordered all schools to close.
Ministers said provisions would be made for pupils whose parents are key workers, such as doctors and nurses, along with certain vulnerable children.
EIS general secretary Larry Flanagan said: "It is absolutely essential that Scotland's local authorities develop models of education provision that will minimise the risk of the spread of the Covid-19 virus amongst students, staff and the wider community.
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"This should be based on the Scottish Government rules on the presumption of schools closing to support social distancing, students and staff working remotely from home where possible and strictly limiting pupils attending hub facilities to the children of key workers without another childcare option and, also, certain categories of vulnerable children."
The union said failing to follow the guidelines could lead to the coronavirus spreading to parents and carers, some of whom may be front-line medical professionals.
Flanagan added: "The clear instruction from the Scottish Government is that the default position is that schools must close, except in exceptional circumstances such as the need to ensure the welfare of vulnerable pupils and to make provision for the children of category one workers.
"These steps are about saving lives – there cannot be any expectation that things in schools will continue as normal.
"We have had a number of local situations reported to us where some councils have acted unilaterally, cutting trade unions out of discussions and making arrangements that have flouted the Scottish Government advice – e.g. holding meetings of large numbers of staff where social distancing is impossible, bringing cohorts of pupil into schools who are neither at risk nor children of key workers, and insisting that teachers be in school buildings for no specific purpose when remote working is the default position recommended by the Scottish Government.
"Employers need to follow the clear health advice which has been published."
Local authority umbrella body Cosla praised the work teachers were doing in the "unprecedented" situation.
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A spokesman said: "Minimising the risk of the spread of the Covid-19 virus among students, staff and the wider community is essential and is our collective primary driver.
"This is a national emergency the likes of which no-one has experienced before."
He added: "Local authorities have made a massive effort on day one to make sure provision is in place in as comprehensive a way as possible.
"We have to learn, be flexible, adapt to local circumstances and adjust our approach where required and every council is fully committed to doing this.
"The dedication of the teaching workforce and the other essential staff who make up the whole school system is greatly appreciated at this unprecedented time."
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